The major objectives of this research are to systematically analyze the effects on behavior of alcohol alone and in combination with other drugs. Using squirrel monkeys as subjects, the research will focus on an examination of alcohol's effect on various behaviors controlled by different environmental events. Once these effects are determined for alcohol alone, further experiments will be conducted to examine the effects on behavior of other drugs alone and, most importantly, in combination with alcohol. Of particular interest in this research are studies which specifically examine the development of behavioral tolerance to alcohol and then assess the effects of drug interactions once tolerance to alcohol has developed. Such experiments will provide a detailed analysis not only of how alcohol alone affects behavior but will also permit a more adequate understanding of the consequences of alcohol-drug interactions.